Polymerized dichlorostyrenes containing organo-tin anticrazing agents



Patented June 23, I953 UNITED "STAT-ES PATENT OFFICE POLYMERIZED .DICHLOROST-YRENES CON- TAINING .ORGANO .TIN ANTICRAZING AGENTS John"W. Churchill; 'Kenmore, N. ?Y., assignor Ito Mathieson Chemical Corporation, :New .York, N. Y .,'a corporation of Virginia No'Drawing. Application August 18, 1948, Serial No. '45;000

.6';OlaimS. (CI. 260-45275.)

This invention relates. to a, method of preventeven when :apparently extensive, on the paring deterioration by crazingof .formed'plasticularly'desirablephysical and electrical proptics. More particularly, the invention provides a erties of' the nuclear chlorinated styrenes. The method of suppressing this unusual phenomena necessity of overcoming this form of crazing is in certain polymerized vinyl. aromatic compounds 5 principallydueto the undesirable appearance of by the incorporation of certain organic tincomthe plastic material. pounds therein, and an improved plastic com- I have-'found-that the incorporation of small position formed therefrom. amounts of certain organo-tin compounds in The phenomenon of crazing inv polymerized polymerized -dichlorostyrenes and theircopolyvinyl aromatic compounds renders the materials 10 mers effectivelyprevents crazing. .By organoobjectionable from a sales viewpoint although tin compo ds 111 fippl I e the the physical properties of crazed samplesdonot 'true organo ti 01111 011 av a a t 0 appear to be adverselyafiected, Grazing is an carbon-tin bond preferably'thetetra substituted internal formationof discontinuity in the plastic '(tet a t) tin c pou Substituting but the cause and nature of the phenomenon is radicals maybe aliphatic orv aromatic or mixed vnot wholly understood. ,Two general types of ilin Iiaturebuttheeromatic'COmpOunds pp -crazing havepreviously been distinguished and 110 be moreisatisfactory'than aliphatica designated as wet and .dry crazing. The D 5 of compounds useful according o y invenformer seems to-ibe due to the segregation of tion re t ph yl in,' ph y1 di hyl tin,

.lation is more extensive if the article is in a monomer residues or ,low molecular Weight poly- 20 d u y d p y -,tetra00ty1 15in. Idiblltyl tin mers and appears as surface roughnesses evenm diblltylvtin phthalate. tetrabutyl tually accompanied by the development f dibutyl tin oxide,.dibutyl tin dilaurate, and dicloudiness. This phenomenon is also known utyl tin.mal0natesometimes as monomer disease. The dry" a n pm Which exemplify m crazing appears as internal cracks of various diof those which. are effective in the present inmensions. vention maybe represented by the following There is still another form of crazing of a I previously unknown character which appears to .111 B:

be peculiar to nuclear chlorinated styrenesand copolymers containing or more of nuclear 3O chlorinated styrenes. It first becomes apparent R1 R4 by the formation of visible spicules in the polyand meric article which may grow in number and extent with time. This type of crazing or spicu- /,S11=Rs 'wherein'Ri and R2 are selected from the group consisting of phenyl and alkyl radicals, R3 and R4 are selected from the group consisting of phenyl, alkyLandlauroyloxy radicals, and R5 annealing as are the previously known types of 00(1) crazing. In some cases, slight improvement in Q11; the prevention of crazing can be efiected by coolmoist atmosphere than in a dry atmosphere. To a slight extent the crazing can be minimized by annealing the molded articlesat'an elevated temperature, for example, 105 0., for several ing the article quickly'in water rather than .al- O 00 lowing it to cool slowly in air, but the extent to which water cooling improves the plastic'in this respect is rather minor. AH This latter form of crazing or spiculationjis further distinguished fromthe other forms in d that it usually increases to a maximum and suban sequently decreases somewhat on standing.

.However, without the treatment'of the present i invention, the decreasein amount of crazing; is

minor in extent and the .product is still unsalable even after long standing. It is important radlcalsto note;that. this: form 'of crazing-= has litle efiect, -My invention is particularly efficacious with respect to polymerized dichlorostyrenes but it is also effective with other vinyl aromatics such as styrene itself and with copolymers of dichlorostyrene, for example, with styrene or other copolymers. Amounts of tetraphenyl tin or other anti-crazing organic tin compounds up to about may be used, but usually one per cent or less is effective, and I particularly prefer to use from 0.05% to 0.5% based on the weight of the polymer.

The anti-crazing tin compound may be introduced into the polymer in any suitable manher, for example, by milling, or it may be dissolved in the monomer before polymerization.

In order to test my compositions, the mo nomers or mixtures thereof were polymerized by known methods with or without my anti-crazing agents dissolved therein. Into some of the polymerized compositions, my anti-crazing agents were incorporated by milling. The test pieces were stored in a desiccator over water for extended periods of observation. The number of days to begin crazing was recorded for each sample when the first spicule became visible. The second feature observed was the number of days for the sample to become fully crazed. This point was judged .to have been reached when it appeared that no additional spicules could form without contacting spicules already present. After further storage spicules began to disappear in some samples and this feature was noted as the time to begin regression. The tests were finally concluded by reporting the total number of days since molding and the beginning of tests together with the per cent of area crazed in that time.

Example I A sample of polymerized dichlorostyrene prepared from the mixed isomeric monomers containing 0.35% of lauroyl peroxide was placed in a desiccator over water for observation. At the same time samples were placed in the desiccator which had been prepared from the same polymerized dichlorostyrene by milling thereinto 0.5%, 1% and 2% of tetraphenyl tin. The untreated sample began to craze in one day and was completely crazed in one additional day. No regression apparently occurred in this sample, and after 135 days storage it was still completely crazed and very cloudy. In all of the samples containing tetraphenyl tin crazing began after 5 days and was complete only after the lapse of 38 days. Regression began after 120 days, and after 135 days the samples were about 90% crazed but still clear.

Samples of the polymerized blank and of the compositions containing tetraphenyl tin were also tested by allowing them to stand in air at room temperature. Both the samples of the blank which were air cooled and water cooled were badly crazed, whereas the sample annealed at 105 C. for 16 hours was about 75% crazed after four months. None of the samples containing tetraphenyl tin, when treated under these conditions, showed any crazing.

Example II A commercially extruded sample of polymerized dichlorostyrene containing no tetraphenyl tin was compared under the same conditions as described in Example I with extruded polymer into which 0.25% and 0.5% of tetraphenyl tin had been milled. The untreated sample began to craze after two days and crazing was complete after 8 days. No regression was noted and after 132 days the sample was cloudy and crazed. On the other hand, the two samples containing tetraphenyl tin began to craze only after four days and required a total of 22 days to complete crazing. After 95 days, regression began and after days was reduced to 75% in the samples containing 0.25% of tetraphenyl tin, and to 50% in the samples containing 0.5% tetraphenyl tin.

When stored in air at room temperature, the untreated sample showed about 10% crazing in the air cooled and water cooled samples but the sample annealed as described in the preceding example showed only about 5% crazing. Substantially no crazing occurred in the samples containing tetraphenyl tin stored under these conditions.

Example III Samples of monomeric dichlorostyrene were admixed with 0.1%, 0.25% and 0.5% of tetraphenyl tin. These solutions and a blank containing no tetraphenyl tin were polymerized under identical conditions. The polymer was ground and injection molded and the test pieces placed in a desiccator over water for observation. The untreated sample was completely crazed in one day and remained so during the entire test of 126 days. The sample containing 0.1% of tetraphenyl tin began to craze in 2 days and was completely crazed in 10 days. Regression began after days and in 126 days was 75% crazed but clear. The sample containing 0.25% of tetraphenyl tin required 3 days before evidence of crazing was observed, and 15 days before being completely crazed. After 65 days, regression began and the sample was only 50% crazed at the end of 123 days. The third sample containing 0.5 of tetraphenyl tin showed crazing after '7 days and complete crazing after 15 days with regression beginning after '73 days, being 50% complete after 123 days.

When air cooled, water cooled or annealed, as described in Example I, the untreated sample was 100% crazed, whereas the sample containing 0.1% of tetraphenyl tin showed 10% crazing in the air cooled and water cooled samples but none in the annealed sample. The samples containing larger percentages of tetraphenyl tin showed no crazing under any of these conditions.

Example IV Tetraphenyl tin to the extent of 0.25% was dissolved in part of another sample of mixed isomers of monomer dichlorostyrene and both this solution and the untreated dichlorostyrene were polymerized under identical conditions. The polymer was ground and injection molded and the test pieces placed in a desiccator over water. The untreated sample was completely crazed in 3 days, whereas the sample containing 0.25% of tetraphenyl tin required 39 days before becoming completely crazed. No regression occurred in the untreated sample and after 120 days it was cloudy and 100% crazed; The sample containing tetraphenyl tin showed regression after 74 days and was only 50 crazed after 120 days. It remained clear throughout the test.

The untreated sample showed 100% crazing whether air cooled or water cooled and 50% crazing when annealed while the sample containing tetraphenyl tin showed no crazing under any of these conditions.

Example V 0.5% of tetraphenyl tin was dissolved in mofnoineric dichlorostyrene and tli polymerized.

' Regression began after 20 days a d The polyfiier 'wa s gr'oiind molded by a commercial molder. Samples' o untreated' polymerized dichlorostyren'e--molded by the same molder showe'd-complete crazing' 'in' 1 *day, "whereas the polymer emmm n taraphenyl tin required days to beg-incr'azih'g.

solvedtherein was polymerized by conv'enti'ofnal-;

means, ground andinjectioninolded. Pin storage over water in a desiccator, brazing was l00%"in 7 days but regression began in 50 days and was reduced to 50% in 68 days. The sample remained clear throughout the" period of test.

Emample VII Samples of untreated monomeric dichlorostyrene, a portion of the same monomer containing dissolved therein 0.5% of tetraphenyl tin, a third portion of the same monomer containing 0.5% of dibutyl diphenyl tin and a fourth sample containing 0.5% of dibutyl tin dilaurate were polymerized under identical conditions using 0.25% of lauroyl peroxide. The polymers were ground and injection molded. The test pieces were stored in a desiccator over water. The untreated sample became completely crazed in 3 days and remained cloudy and crazed for the '72 days it was under observation. The sample containing tetraphenyl tin became completely crazed only after 18 days, and after 27 days regression began. After 76 days substantially all of the crazing had disappeared and the sample was clear. The sample containing 0.5% of dibutyl diphenyl tin was completely crazed after 4 additional days. After 24 days regression began and. amounted to only about after 76 days. The sample containing 0.5% of dibutyl tin dilaurate was completely crazed in 9 days but regression began after 14 days and was reduced to about in 73 days.

None of these samples showed any crazing when annealed at 105 C. for 16 hours and allowed to stand in the air at room temperature. The air cooled and water cooled samples showed some crazing but this disappeared in a few days.

Example VIII Tetraphenyl tin was dissolved in a portion of another sample of monomeric dichlorostyrene, and both the treated and untreated portions were polymerized using 0.1% of benzoyl peroxide. The polymerized, ground and injection molded samples were stored as in previous examples. While the untreated sample became completely crazed in 3 days, the treated sample required 13 days. No regression occurred in the untreated sample, whereas regression began in the treated sample after days, and after 76 days was reduced to about 10%.

Samples of the polymer containing tetraphenyl tin when (a) air cooled (1)) water cooled, and (c) annealed at 105 C. for 16 hours showed no crazing at any time during several months standing in air at room temperature.

Example X Dibutyl tin malonate showed only limited solubility in mixed monomeric dichlorostyrenes.

However, sufficiently dissolved to render the composition craze-free for 10 days in air at room temperature saturated with moisture.

5 Example XI 'A 'sample of mixedisomeric nuclear dichlo- -rostyrenes was saturated with dibutyl tin :phthalate, 0.1% of benzoyl. peroxide was added,

and --the -:c0mpositionipolymerized. .The polymer --was maintainedman-atmosphere saturated with moisture at room temperature for a period of 83 days before the test was discontinued. At that time no crazing had developed.

Example XII A sample of mixed nuclear dichlorostyrenes saturated with dibutyl tin maleate was polymerized using 0.1% of benzoyl peroxide. The polymer remained craze-free for 88 days when maintained at room temperature in air saturated with moisture. The test was then discontinued.

An untreated sample of monomer was polymerized under the same conditions and tested under the same conditions as in the three preceding examples. The blank was badly crazed in three days.

Example XHI and SI1=R5 R2 wherein R1 and R2 are selected from the group consisting of phenyl and alkyl radicals, R3 and R4 are selected from the group consisting of 7 8 phenyl, alkyl, and lauroyloxy radicals, and R5 is po ated t e a small quantity of an antiselected from the group consisting of oxygen, Grazing agent which consists of diblltyl tin C maleate.

' 5. Polymerized dichlorostyrenes having incor- E porated therein a. small quantity of an anti- 000 crazing agent which consists of dibutyl tin -phtha1ate. 00C 3 6. Polymerized dichlorostyrenes having incor- OH porated therein a small quantity of an anti- 11 crazing agent which consists of tetrabutyl tin.

I d JOHN w. CHURCHILL. an

References Cited in the file of this patent 15 UNITED STATES PATENTS 00c Number Name Date 2,267,777 Yngve Dec. 30, 1941 radicals. 2,267,779 Yngve Dec. 30, 1941 2. Polymerized dichlorostyrenes having incor- 2,307,092 Yngve Jan. 5, 1943 porated therein a small quantity of an anti-craz- 2,476,422 Leininger July 19, 1949 ing agent which consists of tetraphenyl tin. 2,477,349 Richard July 26, 1949 3 A polymerized dichlorostyrene according to FOREIGN PATENTS claim 2 1n which the tin compound is present in an amount varying from 0.05% to 5% by Number F -X Date weight, based upon the weight of the polymer. 497-879 Great Bl'ltam 301 1938 4. Polymerized dichlorostyrenes having incor- 

1. POLYMERIZED DICHLOROSTYRENES HAVING INCORPORATED THEREIN A SMALL QUANTITY OF AN ANTICRAZING AGENT WHICH CONSISTS OF AN ORGANO TIN COMPOUND HAVING THE STRUCTURAL FORMULA SELECTED FROM THE GROUP CONSISTING OF: 